Mayor de Blasio is going to oppose a bill in Albany that would boost the pensions of cops hired after July 1, 2009 who retire on line-of-duty disabilities, The Post has learned.

A source said that the mayor supports the men and women in uniform, but opposes the bill because of its cost.

The Post reported Tuesday that the Citizens Budget Commission, a leading fiscal watchdog, has sent a letter to the mayor warning that the pension boost would add $35 million a year to the city budget.

The police union called that figure wildly inflated and said the actual cost would be closer to zero in the first years because only a limited number of cops would initially be eligible, namely those hired in the last five years.